As a general rule, the terminal end of the yarn on a spinning cop is wound by the spinning frame in such a way that it cannot easily be freed at a winding station of a bobbin winding machine and transferred to its appropriate yarn handling members. For this reason it is typically necessary to provide a device or apparatus disposed between the spinning frame and the winding station of the winding machine for prepositioning the yarn end for the subsequent unwinding process. Various preparation devices of this type are known from a number of patents. Basically, in such devices, the yarn end is initially loosened and aspirated into the suction slit of a suction nozzle by essentially pneumatic means of these preparation devices which are, if necessary, aided by means which act mechanically on the cop. During this process, the cop is turned opposite to the winding direction of the yarn to make grasping of the yarn easier and to enable the required length of the yarn to be freed after it has been grasped. Grasping of the yarn end is usually monitored by sensors. A cutting device, disposed at a fixed distance from the suction slit, is used for the exact cutting to a consistent length of the yarn end in order to always have a constant yarn length available for the subsequent yarn prepositioning.
Prepositioning of the yarn can take place in various ways but, as already mentioned, must always assure that problem-free release of the yarn end as well as its supply to the appropriate grasping device of the winding station is possible.
One manner of prepositioning the yarn end on the cop is to wind an endwise length of the yarn about a nose portion of the cop. In doing so, it is possible that the yarn may slacken in traveling from the preparation device to the winding station, particularly in the case of relatively slick yarns. Also, a length of the yarn may be inserted into the cop tube but may be insufficient in length particularly with relatively small cops. Further, the yarn length available for insertion into the tube is limited by the distance between the tip of an arbor of a pallet on which cops are customarily placed and the nose of the cop tube, which must be taken into consideration in order to prevent the yarn end from being jammed between the arbor and the tube thereby preventing the yarn from reaching the yarn handling devices of the winding station.
One possibility for introducing a greater yarn length into the tube is described in German Patent Publication DE 41 14 758 A1, wherein the yarn end is aspirated into an air duct of the arbor. Appropriate retaining elements are located inside this air duct to prevent the continued aspiration of the yarn end.
A further possibility to increase the yarn length provided for grasping at the winding machine is described in Japanese Patent Publication JP 3-120 174 A, wherein a nose winding of yarn is first placed on the nose of the cop tube and subsequently a length of the remaining yarn is aspirated into the tube. In the apparatus which performs this operation, a rod extends from a first station at which the yarn end is sought and grasped to an adjacent station at which the yarn end is deposited. This rod is disposed in the path of the yarn extending between a slit of a suction nozzle, which also extends between these two stations, and the cop itself. The yarn is therefore placed around the rod. The rod is disposed at an appropriate height such that its lower edge is located in the area of the cop nose to be ready for winding. A nose winding is placed on the cop nose with the aid of the rod by rotating the cop in the station in which the yarn deposit is to take place. After cutting the yarn end, the remaining yarn end is aspirated into the tube interior of the cop by means of an air duct extending through the cop and through the arbor and base plate of a pallet supporting the cop. As a result, the loop closes around the rod. The cop is subsequently moved on and drawn over the end of the rod. Because of this relative movement between the cop and the rod, it is possible that the yarn end brought into the tube may inadvertently be pulled out again if the yarn is snagged on the rod, for example because of an unevenness on the rod.